Relationships Between Tomato Earliness Indexes and their Interaction with Cultivation Methods

On the basis of a semidiallel experiment carried out among 11 parental lines, relationships between earliness production indexes (EPI) and earliness temporal indexes (ETI) based both on the yield (Y) and on the number of fruits (N), have been studied. Both earliness temporal indexes (ETI_Y and ETI_N) are correlated with Y, N and Y'N, the genotypic correlation between both indexes being verv high. Genotypic and environmental correlations between ETI_Y and EPI_V and between ET1_N and EPI_N are also high. Moreover, both under open-air cultivation and under plastic-house, temporal eailiness ETI_Y (ETI_N) has a higher influence on early production EPI_Y (EPI_N) than the yield Y (N). Genotypic, environmental and phenotypic correlation between any pair of these characters, show a similar magnitude and are similar also under plastic-houre and in the open-air. Neverthel ss, genotypic correlations between plastic-house and open-air cultivation were extraordinarily low for all the indexes, showing the existence of strong genotype-environment interactions r_g. (ETI)=0 072, r_g. (ETI_S)=0–102, r_g (EPIy)=0 277, r_g (EPI_N) = 0 417. Variance analysis of the combining abilitv belonging to each one oi the indexes, point out high significance both for GCA and SCA. The greater importance of SCA Compared to GCA is noteworthy, particularly under open-air cultivation.